The invention relates to a gas bag restraint system for an occupant of a vehicle.
U.S. Pat. No. 5,322,322 shows a restraint system which is constructed as a head gas bag. The head gas bag is tube-shaped and extends in the inflated state from the A-column obliquely upwards to beyond the B-column. This gas bag, however, only covers a relatively small portion of the side window of the front occupant. A net arranged on the upper edge of the gas bag can only serve as an additional small restraining surface. In addition, the tensioning force applied to the net by the always linearly extending gas bag is probably low, this being the reason why the net can not absorb any higher lateral forces without yielding greatly.
Furthermore, it is known to provide louver-like gas bags which extend from the A-column up to the C-column and are intended to offer protection laterally equally to the front and rear occupants, i.e. from the side window of the front to the side window of the rear occupants. The production of these gas bags, which cover a large area, is relatively expensive. In addition, a tube carrying gas extends along the roof frame, via which tube the gas is to flow as uniformly as possible into the gas bag. The gas volume for inflating this curtain-like gas bag is relatively great, so that extremely powerful gas generators have to be provided, which ensure a sufficiently quick filling.
The invention provides a gas bag restraint system which is simply constructed, is able to be manufactured at a favorable cost and requires a relatively low gas volume despite a very large available restraining surface. The gas bag restraint system according to the invention furthermore distinguishes itself by a great force applied to the tensioning means and giving the tensioning means a stable position. The gas bag restraint system for an occupant of a vehicle according to the present invention comprises a tube-shaped gas bag with a longitudinal axis, which endeavours to extend in a straight line in an inflated state of the gas bag and which has an outer wall. The system further comprises at least one tensioning means arranged on the outer wall, by which tensioning means the gas bag is fastened to the vehicle. The tensioning means is designed with a large area and is arranged at such points of the outer wall and on the vehicle that the longitudinal axis of the tube-shaped gas bag extends in a curved shape in its inflated state. The tensioning means is tensioned by the curved gas bag and forms an additional restraining surface. The tube-shaped gas bag is, therefore, not tensioned between its two axial ends and able to extend linearly between these axial ends, rather, quite on the contrary, it is forced by the tensioning means to assume a curved profile, something which results in a high tensioning force. Thereby, the gas bag braces itself between the tensioning means or the sets of tensioning means and is fixed in position. The tube can above all be curved such that, by itself or together with the tensioning means, it shields regions which can not be covered by a gas bag which extends exclusively linearly, with the result that the gas bag, despite its small volume, can cover those regions of the vehicle which are likely to cause injury (the B-column or the side window on a level with the head).
The tensioning means can be a piece of fabric covering a large area, or a net, on which the gas bag is arrested at several points. For arresting, the gas bag can extend for example through slits in the piece of fabric.
The gas bag restraint system according to the invention is preferably a side impact restraint system and extends in front of one or more side windows.
The gas bag is in particular a fabric tube manufactured so as to be seamless, preferably even endless, which is deflected by the tensioning means by more than 30xc2x0, preferably more than 60xc2x0.